Outlook PST File Too Large to Open & Copy – How to Fix Issue?

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If you are using MS Outlook, you may be concerned about the issue i.e. PST file too large to open. So, in this article, we will explain all aspects related to the Outlook PST file. Read the complete article to find the best solution to compact PST file without opening Outlook problem.

PST files are the Outlook data file. Outlook stores the complete mailbox data in the system as an offline PST file. It is saved in your system and serves various purposes like backup and synchronization with the server. No doubt, the PST files are valuable for all Outlook users.

Any new message in the Outlook application will automatically get updated in these PST files. So, you need not update them regularly. The PST files have a finite storage limit. If you exceed this limit, the PST file will start creating the PST file too large in size problems.

What Causes Outlook PST File too Large in Size?

When you send/receive a new email, the data will get stored in the Outlook data file. So, with increasing mails, the size of the PST file increases. Generally, the file has sufficient space to store a large amount of data, but it has a finite storage capacity.

PST file stores complete mailbox data. So, along with emails, it also saves contacts, calendars, tasks, journals, attachments, etc. Adding more data to these categories will also increase the PST file size. Before learning how to open an Outlook data file, we should explore the size limit of PST files.

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Download the best DRS PST File Splitter software to break, divide or split large-sized PST file into multiple smaller PST.

How Big Can a PST File Be – PST File Size Limitation

The storage capacity of PST files has increased significantly with Outlook updates. Initially, Outlook 2000 and 2002 used to store a maximum of 2GB of data in a PST file. This size limit reached 20 GB in Outlook 2003 and 2007. Now, MS Outlook 2010 and later versions come with a maximum PST size limit of 50 GB.

With a PST file too large to copy, chances of PST file corruption are still there. So, Microsoft developed the built-in free utility i.e. Inbox Repair Tool to fix minor corruption in Outlook PST files. Also, you should maintain the PST file size as an oversized PST will cause various problems to the users.

Problems Arise Due to the PST File too Large Size

Outlook PST files have a fixed storage limit. Beyond that, it starts showing error messages and even leads to file corruption. You become unable to open Outlook data files. Some of the main issues that arise due to oversized PST files are.

  • Outlook Error 0x00040820 – When you try to synchronize an Exchange server with offline files, you may encounter error 0x00040820. The reason behind this Outlook error is an oversized PST file.
  • Cannot Open Outlook Data File – You will encounter an issue like a file cannot be copied because it is too large. Therefore, your PST file should be below the maximum size limit.
  • Outlook PST Corruption – An Outlook.pst file too large in size will also be subject to file corruption. As it is already oversized, adding more data will lead to PST file corruption. So, you will not be able to recover your precious mailbox data.

These are the prominent issues related to the Outlook data file too large size to open problem. So, it becomes necessary to reduce the size of the PST file under its size limit. Let us learn the different viable options through which you can reduce the size of PST files.

Practical Solutions to Reduce the Size of Outlook PST file

Outlook PST files contain all your mailbox data. You cannot simply delete your valuable emails. So, here we explain the most practical ways to reduce the size of a PST file too large to copy. The two standard techniques that do not require any additional tools are

  • Mailbox Cleanup Tool
  • Using the Compact Now Feature

#1. Mailbox Cleanup Tool

  • Launch the MS Outlook application in your system.
  • Click on the File button on the top menu bar.
  • Now, select the Tool icon in the Info tab.


  • After that, choose the Mailbox cleanup option.

mailbox cleanup

  • In the new wizard, click on the Empty button to clean deleted emails permanently.


  • Using this technique, you can compact a PST file too large to copy by emptying the deleted items folder. If this method does not work, you can opt for another technique.

#2. Using the Compact Now Feature

  • Open the Outlook application and click on the File
  • Now, press the Account Settings
  • After that, click on the Account Settings option from the list.

account settings

  • In the new wizard, select the Data Files tab.

data files

  • Choose a particular PST file and click on the Settings button.


  • Now, press the Compact Now button to compress PST files.


  • At last, click on the OK button to finish the process.

In this method, you are not deleting any mailbox data. You are compressing the Outlook file too large to open or copy. Although it is an effective technique, it may cause damage to the PST file. So, it is also not a permanent solution. The most reliable option is to split your large size PST file into smaller files.

Professional Tool to Split PST Files too large in size

DRS PST Splitter is a professional utility to divide large size PST into smaller files. It reduces the size of PST files by distributing the data into multiple files. Therefore, it fixes the issue of the PST file too large to copy or open. The software provides numerous advanced features to make file splitting easy and effective. Moreover, the tool has an interactive user interface so that any novice user can divide the PST files without hassle.


After reading the complete article, it can be concluded that the large-sized PST file is a general issue. You can resolve the problem by various methods. However, they are not the permanent solution. The best option is to divide the PST file too large in size into multiple smaller files. It reduces the PST size without deleting any mailbox data.

Frequently Asked Questions on How can I open a large PST file?

Here, we answer the most common queries regarding the oversized PST file and reducing it without damaging the file content.

Q 1. How do I split a large PST file into smaller parts?

Ans: The best option to split a large PST file into smaller parts is through the DRS PST Converter. Follow the steps below.

  • Download and run the tool administrator.
  • Add desired PST file/files and click Next.
  • Choose the splitting options and proceed further.
  • Select other details and add a password.
  • At last, click on the Split button to divide the PST.

Q 2. My PST file is too large. Can I migrate it?

Ans: You can migrate your PST file unless its size is beyond the maximum size limit. The large-sized PST file will lead to Outlook errors and file corruption. There are different techniques to migrate your PST file. You can opt for either manual or automatic methods.

Q 3. What happens when you compact an Outlook data file?

Ans: On compressing the Outlook data file, the space occupied by these files will reduce greatly. It increases the space available for Outlook functionality. So, the efficiency of Outlook will improve.

Q 4. Can I compact the PST file without opening Outlook?

Ans: Yes, you can compact the PST file without Outlook. The best option is to split the Outlook data file into smaller files. It distributes the size between two PST files and hence reduces the space. You can use a professional PST splitter tool.

Q 5. How can I reduce the size of my PST file without Outlook?

Ans: You can reduce the size of Outlook PST files without Outlook by using the DRS PST Splitter. It divides the mailbox data of a large size PST file into various smaller files. So, the file gets compact significantly.

Q 6. What is the maximum size a PST file can be?

Ans: The maximum size limit of the PST file depends upon the MS Outlook version. For Outlook 2000 and 2003, it was 2 GB. After that, it increases to 20 GB for Outlook 2007. Now, for Outlook 2010 and all later versions, it is 50 GB.

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